Factors driving xanthid crab colonization of oyster reefs (2012)

Undergraduates: Stacy Zhang, none Nathan Geraldi none

Faculty Advisor: Charles Peterson
Department: Biology

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Degradation of oyster reefs from anthropogenic activity has caused changes to reef trophic dynamics including altered community structure. Habitat colonization and the factors that effect species distributions are an important component in determining community structure. The mechanisms that drive mesopredator colonization and utilization of oyster reefs are not well studied in comparison with higher trophic levels and other marine habitats. By manipulating the structural complexity of habitat, food availability, predator presence, and mesopredator density, we sought to elucidate the driving factors of xanthid crab colonization of oyster reefs using a mesocosm and a field experiment. Although no significant differences were found between treatments in the field, average colonization was greatest in low structure habitats with no food. Consumption of food resources was greatest in high structure habitats suggesting that other factors, such as turbidity, may have also acted in conjunction with the factors we tested in the field. In the mesocosm experiment, predator presence and high mud crab density were found to significantly increase colonization of high structure habitats. Complex habitats provide greater space for colonization and protection from predators. There was a trend for food availability to increase colonization in mesocosm experiments. We conclude that habitat structural complexity, predator presence, and xanthid crab density can be important determinants.